Cylinder for hydraulic brakes



Feb. 20, 1940. H. K. WEIHE CYLINDER FOR HYDRAULIC BRAKES Filed April 10, 1937 Patented, Feb. 20, 1940.

UNITED "STATES PATENT OFFICE CYLINDER FOR HYDRAULIC BRAKES Hermann Kurt Weihe, Berlin, Germany Application April 10,1937; Serial No. 136,226

' In Germany April ,11, 1936 3 Claims.

v pipe to the cylinders is complicated and diflicult,

especially in modern vehicles, in which the space available near the wheels is usually rather limited. .As a rule, the brake pipe is connected to the cylinder body at the side by means of a separate connection piece. This connection piece is screwed fast. to the cylinder body by means of a threaded bolt provided with special passages with interposition of copper ring packing-discs. Such a connection however, is not only constructed in a number of parts-and expensive but also the numerous sealing points may easily be the cause of interruptions in operation In particular in the case of faulty assembly or unsatisfactory seating of the packings, it is impossible to avoid the brake fluid escaping from the circuit. More-- over, air can enter the circuit, which is known to be very detrimental for the working of the brakes. Finally, in the known wheel brake'cylinders, the removal of air'from the circuit is effected by the provision of a separate passage in the cylinderbody, which requires a further additional working.

The invention, in contradistinction thereto,

sibleto effect the removal of air through the same pipe throughwhich the brake fluid flows. The

part used for 'connecting the brake pipe has a passage extending transversely to the risingpipe.

This may be provided with a connecting thread l which makes it possible to attach at choice either the air removing screw or the brake pipe, accord- 'ing to which end of the wheel brake cylinder the brake pipe comes to. 'Very favourable conditions for the removal 'of' air from the wheel brake '55 cylinders are obtained if the diameter of the rising pipe in the lateral connecting piece is made greater than the diameter of the brake pipe.

The invention provides for a diminution of the number of parts as compared with the known wheel brake cylinder constructions and also the 5 particular advantage that the separate air-removing passage, which is generally used, is dispensed with. During the air-removing operation the air escapes through the same rising pipe through which the brake fluid is introduced. 10

Two constructions of the wheel brake cylinder for hydraulic brake systems according to the inventionare illustrated in the accompanying drawing.

Fig. 1 is a side elevation of a brake drum in 15 the upper part with incorporated .wheel brake cylinder in part section,

Fig. 2 is a cross-section of the wheel brake cylinder on'the line 11-11 of Fig. 1,

Fig. 3 is a horizontal section on the line IIIIII 2 in Fig. 1, a

'Fig. 4 shows a further constructional form of the invention in cross-section,

' Fig. 5 is a horizontal section through the wheel brake cylinder, according to Fig. 4. 5

In the drawing only those parts of the brake arrangement'areshown which are required for understanding the invention.

1 is the cylindrical wheel brake body arranged between the blocks a within the brake drum 1) 30 with the two spreading pistons slidable therein which enclose. the pressure space I between them. In front of each-of the pistons 2 as usual a packing sleeve 3 is provided, which sleeves are pressed against the ends of the pistons by the 35 spring 4 in the interior of the pressure space I' The pistons 2, which are driven in opposite 'direc tions, act upon the ends of the brake blocks a.

The cylindrical wheel brake body I has, acc'ording to the invention, a branch 5 rising 4o obliquely cast on at the side, which passes through an opening in the cover plate of the brake drum to the so-called brake block carrier 8, see Figs.

2 and 3. The wheel brake cylinder I is secured to thiscarrier bymeans of screws. The lateral 45 branch 5 runs out into a cylindrical extension 1 arranged parallel to the wheel brake cylinder, which has a passage ll provided at each end of the screw threads 9, ID 'for receiving connecting pieces. From the passage II a passage l2 leads to the lower pressure space I of thecylinde r.

This passage opens at the highest point into the pressure space I; as shown in Fig. 2 it forms a rising passage. The two threaded holes 9, l0

serve at choice for connecting the air-removing screw I5 or the brake pipe l4, according to which side the brake pipe H comes from.

In order to remove'air from the brake system. 'when first filled, the air-removing screw l5 on fluid is forced into the whole brake circuit from the main cylinder. The fluid flows through the pipe l4 into the passage II in the cylinder extension 1 of the wheel brake cylinder and further into the outlet-bore of the air-removing screw I5. At the same time a certain quantity of fluid flows through the rising passage l2 into the lower pressure space I ofthe" wheel brake cylinder. This pressure space becomes slowly filled with fluid and the air contained therein collects above the fluid level, which gradually rises, so that the air is forced through the rising passage l2 and finally into the passage II, from which it is finally forced out of the brake system through the outlet bore 20 of the air-removing screw l5.

With a strong uninterrupted pump action the lateral movement of the fluid column in the passage l2 has an ejector-like action on the interior tradistinction to the hitherto usual arrangement in which it'is screwed into the wall of the cylinde transversely thereto. 1

The construction of the wheel brake cylinder according to Figs. 4 and 5 agrees essentially with that shown in Figs. 1 to;3, The principal difference is that the rising passage I2 is made of greater diameter than the brake pipe 25. Owing to this difierence in diameter it has been found that the air can be quickly and reliably removed from the pressure space I of the wheel brake cylinder I. A further difference from. the first constructional example is that the connection of the part I at the free end ofthe lateral extension 5 is provided with a smooth passage I l (without a connecting thread). This passage serves for receiving the connecting nipple 2| at the brake pipe H, which is provided with a pin-like extension 22 on the upper end of which a thread is cut. The extension 22 is tapered for a part .of its length so that between the cylindrical wall of the passage and the extension 22 an annular space is formed. The end of the nipple extension projecting a certain distance out of the passage serves for receiving the cap nut 23 which, when tightened and provided with a locking device 24, ensures. reliable and tight donnection of the brake. pipe l4. As shown in Fig. 5, the nipple extension 22 has a T-shaped passage which provides permanent communication between the brake pipe and the annular space H and the rising passage l2. The connecting part 1 makes it possible to attach the brake pipe 14 from either side. For removing air the cap nut 23 is simply loosened slightly. Then during pump-like operation of the brake a certain quan: tity of the fluid supply from the brake pipe I4 flows through the annular space I I to the opened end of the connecting part I. The other much greater part of the brake fluid flows through the rising pipe I2 into the pressure space i" of the wheel brake cylinder. Since the rising pipeis of greater'diameter than the passage 25 of the nipple 2|, the rising pipe I2 is not able to become filled so rapidly. In this way the air in the wheel brake cylinder is able to escape along the upper part of the cylindrical wall of the rising passage into the bore II, from which it escapes together with the fluid passing out through the loosened cap nut 23. On account of this space, a reliable and satisfactory removal of air from the wheel brake cylinder is obtained. An. essential feature for the invention claimed is the rising passage l2 between the connecting point of the brake pipe and the lower pressure space of the wheel brake cylinder, whereby this rising passage serves both for supplying the brake fluid and for withdrawing the air during the air-removal operation.

What I claim is:

1. A wheel brake cylinder for hydraulic brakes, comprising in combination, a horizontally arranged main pressure cylinder, brake actuating pistons slidable therein, a lateral connecting piece rising obliquely from said cylinder and provided with a single T-shaped passage, the stem of which communicates with said cylinder, one end of the head of said T-shaped passage being connected with a source of fluid for supplying said fluid to said cylinder and the other end of said head being adapted for the escape of air accumulated in said cylinder and removable means for closing said last mentioned end.

2. A'wheel brake cylinder for hydraulic brakes comprising in combination a horizontally 'arranged main pressure cylinder, brake actuated pistons slidable therein, a lateral connecting piece arising obliquely from said cylinder and provided with a single T-shaped passage, the stem of which communicates with said cylinder, a brake pipe fitting, means for connecting said munication between one end of the head of said T-shaped passage and said pipe fitting, the other end of said head being adapted for the escape of air accumulated in said cylinder and removable means for closings said last mentioned end, said closure means and said pipe fitting connecting means being interdependent.

3. A wheel brake cylinder for hydraulic brakes comprising in combination a horizontally arranged main pressure cylinder, brake actuated pistons slidable threin, a lateral connecting piece arising obliquely from said cylinder and provided with a single T-shaped passage, the stem of which communicates with said cylinder, a brake pipe fitting, means for connecting said fitting to said connecting piece to establish communication between one end of the head of said T-shaped passage and said pipe fitting, the other end of saidhead being adapted for the escape of air accumulated in said cylinder and removable means for closing said last mentioned end, the diameter of said passage being greater than the interior diameter of said brake pipe fitting.

HERMANN KURT WEIHE. 

